[FreeReign]

As I went to the mail box, the dog ran over to the middle of the street (perhaps 15 feet away) and bared his teeth.

At the point when the dog bared its teeth, the dog served notice that they are dangerous.

His owners were in the yard but did not call the dog.

At the point when the neighbored ignored the danger, the neighbor served notice that they are inconsiderate.

Call the police.

[Ken H]

At the point when the dog bared its teeth, the dog served notice that they are dangerous.

Exactly right. It should be regarded as a serious threat.